/*
 * math support
 * most of the more complicated code is taken from mesa.
 */

#include <cstdio> // ugly
#include <cmath>

#include <sys/time.h>
#include <time.h>
#include <GL/gl.h>

#include "util.h"
#include "entity.h"

#define DEG2RAD (M_PI / 180.)

void renormalize (sector &s, point &p)
{
  float i;

  p.x = modff (p.x, &i); s.x += (soffs)i;
  p.y = modff (p.y, &i); s.y += (soffs)i;
  p.z = modff (p.z, &i); s.z += (soffs)i;
}

/////////////////////////////////////////////////////////////////////////////

const vec3 normalize (const vec3 &v)
{
  GLfloat s = abs (v);

  if (!s)
    return v;

  s = 1. / s;
  return vec3 (v.x * s, v.y * s, v.z * s);
}

const vec3 cross (const vec3 &a, const vec3 &b)
{
  return vec3 (
     a.y * b.z - a.z * b.y,
     a.z * b.x - a.x * b.z,
     a.x * b.y - a.y * b.x
  );
}

/////////////////////////////////////////////////////////////////////////////

void matrix::diagonal (GLfloat v)
{
  for (int i = 4; i--; )
    for (int j = 4; j--; )
      data[i][j] = i == j ? v : 0.;
}

const matrix operator *(const matrix &a, const matrix &b)
{
  matrix r;

  // taken from mesa
  for (int i = 0; i < 4; i++)
    {
      const GLfloat ai0=a(i,0), ai1=a(i,1), ai2=a(i,2), ai3=a(i,3);

      r(i,0) = ai0 * b(0,0) + ai1 * b(1,0) + ai2 * b(2,0) + ai3 * b(3,0);
      r(i,1) = ai0 * b(0,1) + ai1 * b(1,1) + ai2 * b(2,1) + ai3 * b(3,1);
      r(i,2) = ai0 * b(0,2) + ai1 * b(1,2) + ai2 * b(2,2) + ai3 * b(3,2);
      r(i,3) = ai0 * b(0,3) + ai1 * b(1,3) + ai2 * b(2,3) + ai3 * b(3,3);
    }

  return r;
}

const matrix matrix::rotation (GLfloat angle, const vec3 &axis)
{
  GLfloat xx, yy, zz, xy, yz, zx, xs, ys, zs, one_c, s, c;

  s = (GLfloat) sinf (angle * DEG2RAD);
  c = (GLfloat) cosf (angle * DEG2RAD);

  const GLfloat mag = abs (axis);

  if (mag <= 1.0e-4)
    return matrix (1);

  matrix m;
  const vec3 n = axis * (1. / mag);

  /*
   *     Arbitrary axis rotation matrix.
   *
   *  This is composed of 5 matrices, Rz, Ry, T, Ry', Rz', multiplied
   *  like so:  Rz * Ry * T * Ry' * Rz'.  T is the final rotation
   *  (which is about the X-axis), and the two composite transforms
   *  Ry' * Rz' and Rz * Ry are (respectively) the rotations necessary
   *  from the arbitrary axis to the X-axis then back.  They are
   *  all elementary rotations.
   *
   *  Rz' is a rotation about the Z-axis, to bring the axis vector
   *  into the x-z plane.  Then Ry' is applied, rotating about the
   *  Y-axis to bring the axis vector parallel with the X-axis.  The
   *  rotation about the X-axis is then performed.  Ry and Rz are
   *  simply the respective inverse transforms to bring the arbitrary
   *  axis back to it's original orientation.  The first transforms
   *  Rz' and Ry' are considered inverses, since the data from the
   *  arbitrary axis gives you info on how to get to it, not how
   *  to get away from it, and an inverse must be applied.
   *
   *  The basic calculation used is to recognize that the arbitrary
   *  axis vector (x, y, z), since it is of unit length, actually
   *  represents the sines and cosines of the angles to rotate the
   *  X-axis to the same orientation, with theta being the angle about
   *  Z and phi the angle about Y (in the order described above)
   *  as follows:
   *
   *  cos ( theta ) = x / sqrt ( 1 - z^2 )
   *  sin ( theta ) = y / sqrt ( 1 - z^2 )
   *
   *  cos ( phi ) = sqrt ( 1 - z^2 )
   *  sin ( phi ) = z
   *
   *  Note that cos ( phi ) can further be inserted to the above
   *  formulas:
   *
   *  cos ( theta ) = x / cos ( phi )
   *  sin ( theta ) = y / sin ( phi )
   *
   *  ...etc.  Because of those relations and the standard trigonometric
   *  relations, it is pssible to reduce the transforms down to what
   *  is used below.  It may be that any primary axis chosen will give the
   *  same results (modulo a sign convention) using this method.
   *
   *  Particularly nice is to notice that all divisions that might
   *  have caused trouble when parallel to certain planes or
   *  axis go away with care paid to reducing the expressions.
   *  After checking, it does perform correctly under all cases, since
   *  in all the cases of division where the denominator would have
   *  been zero, the numerator would have been zero as well, giving
   *  the expected result.
   */

  xx = n.x * n.x;
  yy = n.y * n.y;
  zz = n.z * n.z;
  xy = n.x * n.y;
  yz = n.y * n.z;
  zx = n.z * n.x;
  xs = n.x * s;
  ys = n.y * s;
  zs = n.z * s;
  one_c = 1.0F - c;

  m(0,0) = (one_c * xx) + c;
  m(0,1) = (one_c * xy) - zs;
  m(0,2) = (one_c * zx) + ys;
  m(0,3) = 0;
  
  m(1,0) = (one_c * xy) + zs;
  m(1,1) = (one_c * yy) + c;
  m(1,2) = (one_c * yz) - xs;
  m(1,3) = 0;
  
  m(2,0) = (one_c * zx) - ys;
  m(2,1) = (one_c * yz) + xs;
  m(2,2) = (one_c * zz) + c;
  m(2,3) = 0;
  
  m(3,0) = 0;
  m(3,1) = 0;
  m(3,2) = 0;
  m(3,3) = 1;

  return m;
}

const vec3 operator *(const matrix &a, const vec3 &v)
{
  return vec3 (
    a(0,0) * v.x + a(0,1) * v.y + a(0,2) * v.z + a(0,3),
    a(1,0) * v.x + a(1,1) * v.y + a(1,2) * v.z + a(1,3),
    a(2,0) * v.x + a(2,1) * v.y + a(2,2) * v.z + a(2,3)
  );
}

void matrix::print ()
{
  printf ("\n");
  printf ("[ %f, %f, %f, %f ]\n", data[0][0], data[1][0], data[2][0], data[3][0]);
  printf ("[ %f, %f, %f, %f ]\n", data[0][1], data[1][1], data[2][1], data[3][1]);
  printf ("[ %f, %f, %f, %f ]\n", data[0][2], data[1][2], data[2][2], data[3][2]);
  printf ("[ %f, %f, %f, %f ]\n", data[0][3], data[1][3], data[2][3], data[3][3]);
}

const matrix matrix::translation (const vec3 &v)
{
  matrix m(1);

  m(0,3) = v.x;
  m(1,3) = v.y;
  m(2,3) = v.z;

  return m;
}

/////////////////////////////////////////////////////////////////////////////

plane::plane (GLfloat a, GLfloat b, GLfloat c, GLfloat d)
: n (vec3 (a,b,c))
{
  GLfloat s = 1. / abs (n);

  n = n * s;
  this->d = d * s;
}

/////////////////////////////////////////////////////////////////////////////

void box::add (const box &o)
{
  a.x = min (a.x, o.a.x);
  a.y = min (a.y, o.a.y);
  a.z = min (a.z, o.a.z);
  b.x = max (b.x, o.b.x);
  b.y = max (b.y, o.b.y);
  b.z = max (b.z, o.b.z);
}

void box::add (const sector &p)
{
  a.x = min (a.x, p.x);
  a.y = min (a.y, p.y);
  a.z = min (a.z, p.z);
  b.x = max (b.x, p.x);
  b.y = max (b.y, p.y);
  b.z = max (b.z, p.z);
}

void box::add (const point &p)
{
  a.x = min (a.x, (soffs)floorf (p.x));
  a.y = min (a.y, (soffs)floorf (p.y));
  a.z = min (a.z, (soffs)floorf (p.z));
  b.x = max (b.x, (soffs)ceilf  (p.x));
  b.y = max (b.y, (soffs)ceilf  (p.y));
  b.z = max (b.z, (soffs)ceilf  (p.z));
}

/////////////////////////////////////////////////////////////////////////////

struct timer timer;
static double base;
double timer::now = 0.;
double timer::diff;

void timer::frame ()
{
  struct timeval tv;
  gettimeofday (&tv, 0);

  double next = tv.tv_sec - base + tv.tv_usec / 1.e6;

  diff = next - now;
  now = next;
}

timer::timer ()
{
  struct timeval tv;
  gettimeofday (&tv, 0);
  base = tv.tv_sec + tv.tv_usec / 1.e6;
}

GLuint SDL_GL_LoadTexture (SDL_Surface * surface, GLfloat * texcoord)
{
  GLuint texture;
  int w, h;
  SDL_Surface *image;
  SDL_Rect area;
  Uint32 saved_flags;
  Uint8 saved_alpha;

  /* Use the surface width and height expanded to powers of 2 */
  //w = power_of_two (surface->w);
  //h = power_of_two (surface->h);
  w = power_of_two (surface->w);
  h = power_of_two (surface->h);
  texcoord[0] = 0.0f;		/* Min X */
  texcoord[1] = 0.0f;		/* Min Y */
  texcoord[2] = (GLfloat) surface->w / w;	/* Max X */
  texcoord[3] = (GLfloat) surface->h / h;	/* Max Y */

  image = SDL_CreateRGBSurface (SDL_SWSURFACE, w, h, 32,
#if SDL_BYTEORDER == SDL_LIL_ENDIAN	/* OpenGL RGBA masks */
				0x000000FF, 0x0000FF00, 0x00FF0000, 0xFF000000
#else
				0xFF000000, 0x00FF0000, 0x0000FF00, 0x000000FF
#endif
    );
  if (image == NULL)
    {
      return 0;
    }

  /* Save the alpha blending attributes */
  saved_flags = surface->flags & (SDL_SRCALPHA | SDL_RLEACCELOK);
  saved_alpha = surface->format->alpha;
  if ((saved_flags & SDL_SRCALPHA) == SDL_SRCALPHA)
    {
      SDL_SetAlpha (surface, 0, 0);
    }

  /* Copy the surface into the GL texture image */
  area.x = 0;
  area.y = 0;
  area.w = surface->w;
  area.h = surface->h;
  SDL_BlitSurface (surface, &area, image, &area);

  /* Restore the alpha blending attributes */
  if ((saved_flags & SDL_SRCALPHA) == SDL_SRCALPHA)
    {
      SDL_SetAlpha (surface, saved_flags, saved_alpha);
    }

  /* Create an OpenGL texture for the image */
  glGenTextures (1, &texture);
  glBindTexture (GL_TEXTURE_2D, texture);
  glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
  glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
  glTexImage2D (GL_TEXTURE_2D,
		0,
		GL_RGBA, w, h, 0, GL_RGBA, GL_UNSIGNED_BYTE, image->pixels);
  SDL_FreeSurface (image);	/* No longer needed */

  return texture;
}

void draw_some_random_funky_floor_dance_music (int size, int dx, int dy, int dz) {
   int x, z, ry;

   vector<vertex2d> pts;
   for (x = 0; x < 100; x++) {
      for (z = 0; z < 100; z++) {
         pts.push_back (vertex2d (point (dx + (x * size),       dy, dz + (z * size)),       vec3  (0, 0, 1), texc (0, 0)));
         pts.push_back (vertex2d (point (dx + ((x + 1) * size), dy, dz + (z * size)),       vec3  (0, 0, 1), texc (1, 0)));
         pts.push_back (vertex2d (point (dx + ((x + 1) * size), dy, dz + ((z + 1) * size)), vec3  (0, 0, 1), texc (1, 1)));
         pts.push_back (vertex2d (point (dx + (x * size),       dy, dz + ((z + 1) * size)), vec3  (0, 0, 1), texc (0, 1)));

         entity_quads *q = new entity_quads;
         q->set (pts);
         pts.clear ();
         q->show ();
      }
   }
}

//skedjuhlar main_scheduler;